1. Field of the Invention
The present invention relates to an organic electroluminescent display.
2. Description of the Related Art
Organic electroluminescent (organic EL) displays are self-emitting type thin displays, and have advantages of display performance such that high in visibility, and free from viewing angle dependency, as compared with liquid crystal displays. Further, in addition to the advantages of capable of making weight light and thinning, they have the possibility of realizing new shapes of displays that have been unrealized hitherto by using flexible substrates.
Organic EL displays have excellent characteristics as described above. However, since transparent electrically conductive materials having a high refractive index such as ITO are used as the electrode, layers having different refractive indexes are laminated, or metallic materials having a high reflectance are used, sometimes there arise problems such that outer lights are reflected in the interfaces of these layers to cause the reduction of contrast and mirroring in due to internal reflection.
To suppress adverse influences by reflection of outer lights, it is proposed to use an absorption type linear polarizing plate and a circular polarizing plate comprising a ¼λ plate (see JP-A-2003-332062 (The term “JP-A” as used herein refers to an “unexamined published Japanese patent application”,)). However, when a circular polarizing plate comprising a ¼λ plate is used, the use efficiency of light worsens and luminance lowers due to absorption by the polarizing plate.
It is proposed to use a circular polarizing plate having a light diffusing layer as the front plate (edge, refer to JP-A-2004-191450). However, it is anticipated that the Ra) of the light use efficiency of light is bad by the use of the circular polarizing plate and luminance lowers.
A circular polarizing plate is used in JP-A-2003-332068 and JP-A-2004-191450, so that the manufacturing costs increase. As the means in place of this, it is disclosed to provide a colored layer instead of the circular polarizing plate (e.g. JP-A-2005-317271). However, his technique is also not sufficient in the use efficiency of light, and the improvement of the tint of display is desired.